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A variant of the above scenario is using two independent CZ, which share parts of DZ, specifically CouchBase. CouchBase replication is used to ensure HA for this instance. No other parts of DZ, e.g. MZDB and CZ file systems, are shared.<picture>
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This gives zero-time failover in case of Diameter use cases, while session state replication allows fail- over from one site to the other. A requirement for this is that sticky sessions are used when accessing DZ.
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